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Cable wonkiness

Owlie2012-04-07 17:15:31 +0000 #1
I tried the barrel adjusters today to address some of the derailleur problems I've been having. It worked, to a point.

For some reason, I now have a ton of slack in the front shifter cable (and therefore I can't shift into the middle or large chainring). I've tried loosening the bolt that holds the cable in place and manually pulling the cable taut, but there just isn't enough cable there. The same area of the cable (I marked it with a sharpie before I started) ends up at the screw every time. Yet there's still slack in the cable!

Any ideas?
OakLeaf2012-04-07 17:26:05 +0000 #2
Do you have the shifter at the lowest gear position before you start?
Owlie2012-04-07 17:38:46 +0000 #3
Quote:

Originally Posted by OakLeaf

Do you have the shifter at the lowest gear position before you start?

Yes. I was using the directions in the repair book as a starting point (and proceeded to accomplish little more than getting grease all over the book. Horrifying!)
OakLeaf2012-04-07 17:44:11 +0000 #4
Holding the cable with a pair of pliers? It can be hard to hold it taut with fingers while tightening the bolt. If you're going by the book, I assume you tightened the barrel adjusters all the way short before you started, also. (Make sure the pieces of the barrel adjuster are engaged - I've screwed them all the way apart before, and it can be a little tricky getting them back together.)

Also, a service manual without grease on the pages is no service manual at all.
Owlie2012-04-07 18:25:24 +0000 #5
Thanks for the tip on pliers. Not that it did anything in this case, but made it much easier to grip!

The fact that I can keep turning the barrel adjusters clockwise (I assume that's "tight" because that's how everything else is) to no effect is a bit worrying. I don't think there's THAT much extra cable normally.

(Seriously, there's enough slack that I can touch the cable to the frame!)
DebW2012-04-07 19:20:10 +0000 #6
Is the cable frayed? Look inside the shift lever. Is the housing frayed, wires sticking out of it, or the ferrule worn through? Could the cable anchor bolt on the deraulleur be stripped? Is the cable not running under the bottom bracket correctly?
Owlie2012-04-07 17:41:44 +0000 #7
Quote:

Originally Posted by DebW

Is the cable frayed? Look inside the shift lever. Is the housing frayed, wires sticking out of it, or the ferrule worn through? Could the cable anchor bolt on the deraulleur be stripped? Is the cable not running under the bottom bracket correctly?

Cable bolt's good. (The slack is between the plastic thing under the bottom bracket that holds the cables and the shift lever, somewhere. I imagine a stripped cable anchor bolt would result in slack all the way through. Am I correct?) Cable seems to be running under the bottom bracket correctly. (I even cleaned out a bunch of gunk in that area.)

At risk of sounding thick, how exactly would I go about looking for a frayed cable, and where, within all the stuff up there? (My shift levers have that freaking thumb trigger, being Sora, so that may impact where I have to look. The book is not helping here.)
lph2012-04-07 18:32:13 +0000 #8
Quote:

Originally Posted by Owlie

(The slack is between the plastic thing under the bottom bracket that holds the cables and the shift lever, somewhere.

The spring that pulls the cable taut(ish) after you've shifted gears is in the derailleur. If the cable is tight between the derailleur and the bottom bracket, then the der is working and as you said, the slack is elsewhere.

Check one more time that the cable moves freely and smoothly under the bottom bracket. I found out after a ton of trouble that my cable had dug a v-shaped gouge into the plastic bottom bracket thingy, and was sticking there. I fixed it by taking the cable out and reshaping the gouge into a u-shape carefully with a thin drill bit.

Otherwise I'd suspect a fraying cable too. When that happens a cable can grow more and more slack as it gradually unravels. Usually happens inside the shifter lever, but I don't know your type of levers well.

PS. Barrel adjusters work by lengthening the housing, i.e. giving the cable a longer way to travel, ie. tightening the cable, when you screw them out. So start by screwing the barrel adjusters all the way in, clockwise* (you can see them growing longer or shorter after a few turns, you want them as short as possible) before you start tightening the cable by hand. If you've screwed them a bit too far out in advance they de-attach and can be a little fiddly to re-attach. Check by wiggling it sideways.

(*I get the feeling I may be confusing barrel adjusters on brake and gear wires here. Please correct me if I'm remembering wrong, fellow mechanics )

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